This invention relates to a tractor unit and wheeled trailer combination.
A tractor unit can be used to propel a wheeled vehicle, such as an articulated trailer, and usually is provided with a so-called xe2x80x9cfifth wheelxe2x80x9d coupling, to which the forward end of the trailed vehicle is detachably coupled. In order to un-couple the vehicle, it is necessary to extend temporary support legs which support the forward end of the vehicle, and then to allow the fifth wheel coupling and the trailer coupling to be un-coupled, whereby the tractor unit can move away while leaving the trailer stationary and in a safe and stable position e.g. at an unloading bay, or parked in a trailer park.
Known fifth wheel couplings can compensate for any minor vertical misalignment between a trailer coupling and the tractor coupling, in that if the trailer coupling is too high, the fifth wheel coupling can be reversed into a receiving position below the trailer coupling, and then the forward end of the trailer can be lowered until the trailer coupling can enter a mounting socket in the fifth wheel coupling, to complete the coupling connection.
In the event that the trailer coupling is too low (by a small amount), inclined guide surfaces on the fifth wheel coupling can engage the trailer coupling and progressively raise the forward end of the trailer until the trailer coupling is able to drop into the mounting socket, again to complete the coupling connection.
However, in the event that there is substantial vertical misalignment between the trailer coupling and the fifth wheel coupling, this will usually involve some substantial manual adjustment of the height of the forward end of the trailer, by suitable adjustment of the support legs, and with care being taken that this results in the height of the trailer coupling being suitable then to allow easy engagement between the fifth wheel coupling and the trailer coupling.
In one aspect the present invention is concerned with an improved means of mounting a fifth wheel type coupling on a tractor unit, to permit its height to be adjusted to allow easy coupling together of the tractor unit and a wheeled vehicle to be coupled therewith, and without need to carry out any adjustment in the height of the coupling end of the wheeled vehicle.
According to one aspect of the invention there is provided a tractor unit for propelling a wheeled vehicle, when the latter is coupled therewith, said tractor unit having a vehicle coupling unit, and said wheeled vehicle having a coupling for co-operation therewith, and in which the coupling unit on the tractor unit is adjustably mounted on a supporting frame of the tractor unit, so as to be capable of being adjustable in height to align itself with the height of the coupling of the wheeled vehicle when the latter is free-standing in a separated position.
By providing an adjustable-in height coupling unit on the tractor unit, the tractor unit can be manoeuvred easily, with suitable adjustment of the height of the coupling unit, so as to bring the coupling unit of the tractor and the coupling of the vehicle into close co-operation with each other, and without need for any vertical adjustment of any usual temporary support legs at the coupling end of the wheeled vehicle.
The vehicle coupling unit on the tractor unit may be a female type of coupling plate, and the co-operative coupling on the vehicle may comprise a male type of coupling.
The female type of clamping plate on the tractor unit may take the form of a xe2x80x9cfifth wheelxe2x80x9d type of coupling, known per se, and any suitable lifting mechanism may interconnect the coupling and the supporting frame of the tractor unit, to provide necessary upward and downward adjustment of the height of the coupling. This may comprise a hydraulically operated actuator mechanism.
Evidently, in addition to facilitating coupling together of the tractor unit and a stationary wheeled vehicle e.g. an articulated trailer, when in the parked position, the facility to adjust the height of the coupling on the tractor unit will also facilitate un-coupling. Thus, the wheeled vehicle can be manoeuvred into a required parked position e.g. in a loading bay, and then suitable temporary support legs can be extended to support the coupling end of the trailer, and then the adjustable coupling on the tractor unit can be lowered thereby allowing the tractor unit to separate from the vehicle.
It should be understood that a tractor unit according to the invention may be coupled with any type of wheeled vehicle, to propel the latter, and including articulated trailers, mobile screening plants, and other mobile equipment of the type used in quarry sites e.g. a crushing plant, a crushing and screening plant, and a discharge conveyor or elevator.
Preferably, the tractor unit has a pair of endless tracks, to provide for easy manoeuvrability, and also to improve traction when hauling a wheeled vehicle (when coupled with it) over adverse ground conditions.
The tractor unit may have a driver""s cab, mounted on the support frame at any convenient point, preferably the forward end. However, the invention also includes possibility of the tractor unit being remotely controlled, via remote control from remote hand held control units and preferably by infra-red control.
In a separate aspect of the invention, a tractor unit and mobile screening plant combination is provided, and which optionally is provided with a coupling between the tractor unit and the mobile screening plant as defined in said one aspect of the invention above.
According to a further aspect of the invention, there is therefore provided a tractor unit and a mobile screening plant combination, in which the tractor unit is intended to propel the combination, and the mobile screening plant comprises a towable frame or chassis having one or more wheel sets at a rear end, and a coupling at its forward end by which it can be coupled, preferably detachably coupled, with a suitable coupling provided on the tractor unit. The screening plant is intended to screen particulate material, and having a screen box or screen grid, means for supplying bulk material thereto, and one or more discharge conveyors for discharging screened material, such discharge conveyor(s) being arranged to discharge in one or more of the following directions:
a) rearwardly of the plant
b) laterally to one side of the plant;
c) laterally to an opposite side of the plant; and
d) in all of these directions if required.
In a quarry or other environment, it is desirable to provide mobile screening plants, which can receive supplies of bulk material to be screened, eg from a tipper truck, a bucket loader, or a supply conveyor, and which can then screen the material into at least one screened fraction, although preferably more than one, and then can discharge the screened material to suitable stockpiles. In order to use up the space available for stock piling most advantageously, it will be highly desirable to provide a manoeuvrable tractor unit/screening plant combination, and the invention, in a further aspect, seeks to achieve this objective. In particular, the length of the tractor unit, relative to the overall length of the screening plant, is small, and with a pivotal coupling at the forward end of the screening plant, and one or more wheel set at the rear end, and also with preferred arrangement of endless tracks to propel the tractor unit, a highly manoeuvrable combination is obtained. The screening plant therefore can be caused to rotate about a generally vertical axis, passing generally in the region of the axle of the wheel set, and with one or more laterally projecting discharge conveyor deployed to discharge screened material, a progressively increasing circular array of stockpiles can be formed.
Alternatively, with at least one side discharge conveyor in the deployed position, and preferably with one projecting from each side, and optionally with a so called xe2x80x9ctail conveyorxe2x80x9d also deployed, the tractor unit may, for some requirements, be caused to move forwardly in intermittent steps, so that the discharge end of each conveyor discharges successive stock piles, so that two or three lines of progressively increasing length of stockpiles can be formed. This allows the available space to be used most efficiently, and the manoeuvrability of the combination contributes significantly to this advantage.
The tractor unit may have a driver""s cab, or may be arranged to be remotely operable, eg by radio or preferably infra red remote control.
The engine to operate the tractor unit may be provided on the chassis of the tractor unit, and may also serve as a source of motive power to operate the screening components of the screening plant. Alternatively, a power plant may be provided on the chassis or frame of the screening plant, to operate the screening components, and means may be provided also to transmit power from this power plant, eg by operating a hydraulic pump and motor combination, to provide necessary power to operate the tractor unit, which as mentioned above, preferably has a pair of endless tracks.